Fluidics system

ABSTRACT

The present invention provides a fluidics system and a method for selectively drawing fluid from at least one selected reservoir into a channel by providing a negative pressure source downstream of the fluid and channel and selectively back filling the selected reservoir with a gas.

This application is a divisional application of U.S. patent applicationSer. No. 09/917,649, filed on Jul. 31, 2001 and incorporated byreference, which claims the benefit of U.S. Provisional Application No.60/231,548, filed on Sep. 11, 2000.

FIELD OF THE INVENTION

This invention relates to methods and systems of controlling fluid flow.This invention also relates to methods and systems of fluid flow controlfor sample analysis and methods, and systems of fluid flow control inportable fluidics systems.

BACKGROUND

Fluid control is necessary for many systems capable of automatedchemical and biochemical analysis. These systems typically requireliquid samples, reagents, and buffers to be dispensed in a controlledmanner. Making these analysis systems portable presents unique demandson fluidics systems that have not been successfully met by currentlyavailable technology. These demands stem from the combined requirementsof automation, compact size and compatibility with unprocessed samples,especially for field operations or point-of-care applications.

For laboratory-scale devices, there is an assortment of mechanicalvalves suitable for fluid handling and control. However, the size ofthese components makes them impractical for portable analysis systems.While small valves of analogous design have been developed and arecommercially available, as the valve size is reduced, clogs by thecomponents of complex sample matrices become an important limitation.

Micro-total analysis systems (F-TAS) perform integrated chemicalanalysis and fluid control on the micron scale. Many of these systemsare capable of valveless fluid control by means of electrokineticpumping and switch-driving pressures. (Manz, A. et al. in Micro TotalAnalysis Systems; and van den Berg, A. et al., Academic Publishers,Dordrecht, 1995, pp. 5-27). However, micron-scale channels can becomeclogged when unprocessed environmental and clinical samples are used. Inaddition, materials can be adsorbed onto channel walls and interferewith osmotic pumping. Furthermore, these devices have a relativelylow-volume throughput making them impractical for the analysis ofmilliliter volumes, as may be required for accurate measurement of traceconstituents or analysis of inhomogeneous samples.

The need for intermediate scale fluid handling systems has beenidentified. (VerLee, D. et al., Technical Digest, Solid-State Sensor andActuator Workshop, 1996, pp. 9-14) Among the developments in this areaare pneumatic diaphragm valves integrated directly into the device'sfluidics channels. This approach provides fluid regulation while addingonly slightly to the overall size of the system. However,diaphragm-based valves can suffer from sticking, clogging, andperformance loss due to diaphragm aging.

Valveless fluid control has also been developed, thus eliminating theproblem of valve clogging by suspended contaminants. For example,pressure control and pressure differentials can switch fluid flowbetween micro-channels. (Brody, J. P., 1998, U.S. Pat. No. 5,726,404)According to Brody (col 3, lines 30-62):

-   -   The term microchannel is used herein for a channel having        dimensions which provide low Reynolds number operation, for        which fluid dynamics are dominated by viscous forces rather than        inertial forces. The ratio inertial forces to viscous forces is

$R = {\frac{\rho \left( {\frac{\delta \; u}{\delta \; t} + {\left( {u \cdot \nabla} \right)u}} \right)}{\eta \; {\nabla^{2}u}} = {\frac{\rho \; d^{2}}{\eta\tau} + \frac{\rho \; {ud}}{\eta}}}$

-   -   where u is the velocity vector, ρ is the fluid density, η is the        viscosity of the fluid, d is the characteristic dimension of the        channel, and τ is the time scale over which the velocity is        changing (where u/τ=δu/δτ). The term “characteristic dimension”        is used herein for the dimension which determines Reynolds        number, as is known in the art. For a cylindrical channel it is        the diameter. For a rectangular channel, it depends primarily on        the smaller of the width and depth. For a V-shaped channel it        depends on the width of the top of the “V”.    -   Fluid flow behavior in the steady state, τ→∞, is characterized        by the Reynolds number, Re=ρur/η. Because of the small sizes and        slow velocities, microfabricated fluid systems are often in the        low Reynolds number regime (Re<1). In this regime, inertial        effects, which cause turbulence and secondary flows, are        negligible; viscous effects dominate the dynamics.    -   Since the Reynolds number depends not only on channel dimension,        but on fluid density, fluid viscosity, fluid velocity and the        timescale on which the velocity is changing, the absolute upper        limit to the channel diameter is not sharply defined.        This method of fluid control is based on the application and        regulation of differential pressures to each fluid channel and        is only applicable in the low Reynolds number regime. The        regulation of differential pressures makes the design inherently        complex and, further, the requirement for pressure sources and        regulators limits the feasibility of this method for portable        instrumentation. The limitation with regard to the low Reynolds        numbers regime makes the method impractical for the control of        aqueous fluids in channels greater than approximately 100        microns. (Brody J. P. et al., Technical Digest, Solid-State        Sensor and Actuator Workshop, 1996, pp. 105-108; and Brody J.        P., Biophysical Journal, 1996, 71, pp. 3430-3441). Although        valves may not be clogged with these approaches, the fluid        channels themselves are likely to be clogged by suspended        contaminants. Electrokinetic pumping and switching systems have        also accomplished valveless fluid control in micron-scale        devices. (Manz et al., Advances in Chromatography, 1993, 33, pp.        1-67.) Similarly, however, these designs are limited to the low        Reynolds number regime, where micron-scale channels are prone to        clogging. Further, these methods require large driving        potentials, typically on the order of a kilovolt, and fluid flow        that can be drastically affected by sample components adhering        to the wall of the channel.

SUMMARY

According to certain embodiments, the present invention provides afluidics system and a method for selectively drawing fluid from at leastone reservoir into a channel by providing a negative pressure sourcedownstream of the fluid and channel and simultaneously back filling thereservoir with a gas. For example, the present invention may comprise afluidics system comprising an enclosed first reservoir having a firstadjustable vent; an enclosed second reservoir having a second adjustablevent; a primary fluid channel; a first passageway for receiving a firstfluid from the first reservoir and connected to the primary fluidchannel; a second passageway for receiving a second fluid from thesecond reservoir and connected to the primary fluid channel; and anegative pressure source downstream of the primary fluid channel. Thenegative pressure source is configured for moving the first fluid butnot the second fluid to the primary fluid channel when the firstadjustable vent is not in a closed position and the second adjustablevent is in a closed position; for moving the second fluid but not thefirst fluid to the primary fluid channel when the second adjustable ventis not closed and the first adjustable vent is closed; and for movingthe first and second fluids to the primary fluid channel when the firstand second adjustable vents are not closed.

According to certain embodiments, the present invention provides afluidics system and a method for selectively drawing fluid from at leastone reservoir. The fluidics system may comprise a primary fluid channelcomprising an input and an output; a first sealable reservoir comprisinga first fluid output fluidically connected to the primary fluid channelinput, and a first vent configured to selectively seal and unseal saidfirst reservoir; a second sealable reservoir comprising a second fluidoutput fluidically connected to the primary fluid channel input, and asecond vent configured to selectively seal and unseal said firstreservoir; and a negative pressure source connected to the primary fluidchannel output. The system can be configured to selectively draw atleast one fluid from at least one of the first and second reservoirsinto the primary fluid channel when the negative pressure source isactivated and the respective reservoir is unsealed.

The present invention also involves a portable analysis system forconduction of biochemical and/or chemical analysis that contains athree-dimensional fluid circuit; a first enclosed reservoir having afirst adjustable vent; a second enclosed reservoir having a secondadjustable vent; a first passageway for receiving a first fluid from thefirst reservoir; a second passageway for receiving a second fluid fromthe second reservoir; a primary fluid channel; a first connectingchannel connecting the first passageway to the primary channel; a secondconnecting channel connecting the second passageway to the primarychannel; a multimode waveguide; a barrier configured to prevent fluidflow between the first and second connecting channels; and a negativepressure source downstream of the primary fluid channel. The first andsecond reservoirs and passageways are elements of the fluid circuit. Thefluid circuit has elements and a series of layers and at least one ofthe elements is formed using molding techniques, and at least partialelements are formed by molding and mechanical, chemical, thermal andoptical etching. Each layer of a series of layers is at least a partialelement of the fluid circuit. The layers are fused together to form acomplete element of the fluid circuit. The negative pressure source isconfigured for moving the first fluid but not the second fluid to theprimary fluid channel when the first adjustable vent is not in a closedposition and the second adjustable vent is in a closed position; formoving the second fluid but not the first fluid to the primary fluidchannel when the second adjustable vent is not closed and the firstadjustable vent is closed; and for moving the first and second fluids tothe primary fluid channel when the first and second adjustable vents arenot closed.

The present invention involves a method of performing a biochemicalanalysis, having the steps of moving a first fluid in a first reservoirhaving an adjustable first vent to a primary fluid channel when saidfirst adjustable vent is not in a closed position and not moving asecond fluid in a second reservoir having a second adjustable vent in aclosed position when a negative pressure source is activated downstreamof said primary fluid channel; and analysing a first fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, are incorporated in and constitute a part ofthis specification, and illustrate several embodiments of the invention.

FIG. 1 is a schematic representation of a two-reservoir fluidics systemaccording to the present invention.

FIG. 2 is a schematic representation of a multi-positioned valve forconnecting a reservoir to a given source.

FIG. 3 is a schematic representation of a two-reservoir fluidics systemwith serial and parallel fluid channels, multiple negative pressuresources, and an auxiliary fluid reservoir.

FIG. 4 is a schematic representation of a three-reservoir fluidicssystem with venting valves controlled by a controller.

FIG. 5 is a schematic representation of a three-samplereservoir/chamber, two-reagent reservoir, and multiple fluid channelfluidics system with a system relief vent.

FIG. 6 shows fluorescent signals corresponding to the switching of atwo-reservoir fluidics system.

FIG. 7 is a schematic representation of a series of layers of a fluidicscube.

FIG. 8 is a three-dimensional perspective view of a simplifiedtwo-sample reservoir, two-reagent reservoir fluidics system.

FIG. 9 shows an image of an analysis performed with a fluidics system.

FIG. 10 illustrates a summary of the analysis results from FIG. 9.

DESCRIPTION OF CERTAIN EMBODIMENTS

Reference will now be made in detail to certain embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings.

The section headings used herein are for organizational purposes only,and are not to be construed as limiting the subject matter described.All documents cited in this application, including, but not limited topatents, patent applications, articles, books, and treatises, areexpressly incorporated by reference in their entirety for any purpose.

According to certain embodiments, the present invention provides afluidics system and a method for selectively drawing fluid from at leastone reservoir. As shown in FIG. 1, a fluidics system 100 can include aprimary fluid channel 110 having an input end 112 and an output end 114;a first enclosed and sealable reservoir 116 having a first fluid inputduct 118 fluidically connected to the primary fluid channel input end112, and a first vent 120 configured to selectively seal or unseal (openor close) the first reservoir; a second sealable and enclosed reservoir122 having a second fluid input duct 124 fluidically connected to theprimary fluid channel input end 112, and a second vent 126 configured toselectively seal or unseal (open or closed) the second reservoir; and anegative pressure source 128 connected to the primary fluid channeloutput end 114. The system can be configured to selectively draw atleast one fluid, 130 or 132, from the first and/or second reservoir, 116or 122. The fluid is drawn through the first or second input duct,passageways, 118 or 124, into the primary fluid channel, 110, when thenegative pressure source, 128, is activated and the selected reservoiris unsealed by opening its vent, 120, 126. Gas can occupy space 134above the fluids, 130, 132 within the reservoirs, 116, 122. Thereservoir is enclosed except for an adjustable vent which can beassociated with a valve, 136.

It should be understood that, as used herein, “sealable”, “sealed”,“unsealed”, “open”, “opened”, “close”, and “closed” and grammaticalvariants thereof refer to the ability of a fluid to flow in or out of anelement, such as a reservoir, or to the state of the vent that permitsor prevents fluid flow. A fluidics element, such as a reservoir, isunderstood to be sealed when fluid can not readily flow out of thereservoir without, for example, creating a (at least partial) vacuum inthe reservoir.

For example, as shown in FIG. 2, reservoir 216 having a fluid 230, a gasspace above the fluid, 234, an input fluid duct 218 and a vent 220connected to a valve 236 that is sealed when the valve 236 is closed. Asdiscussed further below, the reservoir 216 can also be in a sealedposition when it is connected, via, for example, by the vent 220 andvalve 236, to a negative pressure source 228. The reservoir 216 isunsealed when it is connected, via, for example, by the vent 220 andvalve 236 to the atmosphere. As discussed further below, the reservoir216 can also be in an unsealed (or vented) position when it isconnected, via, for example, by the vent 220 and valve 236, to apositive pressure source 238.

According to certain embodiments, sealed and unsealed can be relativeterms, when the sealed reservoir is connected to a relatively lowpressure source, and the unsealed reservoir is connected to a relativelyhigh pressure source. Further, as discussed below, a vent can beconnected not only to pressure sources, but to additional fluid sources,such as an auxiliary fluid source, as well. Moreover, as discussedbelow, a single multi-positioned valve can be used to regulate theconnection of multiple reservoirs or chambers.

It should be understood that, as used herein, the characterization of apressure source as positive or negative is in reference to atmosphericpressure. Additionally, “negative” and “positive” can be consideredrelative terms when used together to differentiate between multiplepressure sources. For example, a negative pressure source is a pressuresource that has or provides a pressure of less than atmospheric pressureor less than a positive pressure or provides a suction. A positivepressure source is a pressure source that has or provides a pressure ofgreater than atmospheric pressure or greater than a negative pressure.Atmospheric pressure (also understood to be a pressure source) isunderstood to be the local pressure of the atmosphere, and is notnecessarily limited to standard atmospheric pressure, and can be eithernaturally occurring or artificially generated.

According to certain embodiments, the system can have multiple fluidchannels, such as more than one primary and/or multiple secondary fluidchannels, when a given primary fluid channel includes at least twosecondary fluid channels. For example, the primary fluid channel candeliver fluid into a first and a second secondary fluid channel, eachsecondary channel having an input end and an output end or the secondaryfluid channels can function as the primary fluid channel. The multiplefluid channels can be connected in serial fashion for serial fluid flow,in parallel fashion for parallel fluid flow, or any combination thereof,such that some of the multiple fluid channels are connected in parallelwhile others are connected in serial.

For example, as shown in FIG. 3, the primary fluid channel 310 can beconnected to secondary channels. The first 340 and second 342 fluidchannels can be fluidically connected in series or the fluid channels344, 346, 348 can be connected in parallel. The first 316 and second 322reservoirs can be fluidically connected to input ends of the fluidchannels. The connections can either be direct connection, or can beindirect, such as, for example, via a manifold 350, conduit, or otherconnection element.

According to certain embodiments, the system can be configured toselectively draw fluid from at least one of the first and secondreservoirs into both the first and second secondary fluid channels whenthe negative pressure source is activated and the respective reservoiris unsealed. For example, in the case of fluid flow from the firstreservoir, the first reservoir duct can be connected via a 1-2 manifold.The manifold connects to the output end of the first reservoir duct and,on the other end, connects to both the first and second primary fluidchannels. According to certain embodiments, the inverse connectionscheme, where two reservoirs are connected via a 2-1 manifold to asingle fluid channel, is also possible. Thus, according to certainembodiments, the system can further include a manifold, to connect theoutput ends of the first and second secondary fluid channels to thenegative pressure source. The manifold is not limited to 1-2 or 2-1manifold, but can include any number of input and output connections.

According to certain embodiments, including, for example, embodimentscontaining multiple primary and/or secondary fluid channels, thenegative pressure source can include multiple negative pressure sources.For example, as shown in FIG. 3, the negative pressure source cancontain first 328 and second 352 negative pressure sources. The first328 and second 352 negative pressure sources can be connected, forexample, to the output ends of the fluid channel (downstream) 344, 346,and 348 as shown in FIG. 3, respectively. According to certainembodiments, the first and second negative pressure sources can or cannot be independent negative pressure sources, and can or can not beconfigured to operate sequentially and/or simultaneously.

According to certain embodiments of the present invention, the systemcan be configured to selectively draw fluid from the first and/or thesecond reservoir into the first and/or the second secondary fluidchannel when the negative pressure source that is connected (downstream)to the secondary fluid channels is activated and one or both of thereservoir's vent is unsealed, open.

For example, as shown in FIG. 3, if the first reservoir were unsealedand the second reservoir were sealed, and if the negative pressuresource, 352, were activated, fluid in the first reservoir would beselectively drawn into both fluid channels, 346, 348. The secondaryfluid channels, 346 and 348, are in a parallel position.

As another example, if the first reservoir were sealed and the secondreservoir were unsealed, and if the negative pressure source, (connectedto two parallel secondary fluid channel output ends) were activated,fluid from the second reservoir would be selectively drawn into at leastone of the secondary fluid channels.

As yet another example, the first negative pressure source 328 isconnected to the output end of the first fluid channel 344 and thesecond negative pressure source 352 is connected to the output end of asecond fluid channel, 346 and 348. If the first reservoir were unsealedand the second reservoir were sealed, and if the first negative pressuresource 328 were activated, fluid from the first reservoir would beselectively drawn from the reservoir into the first secondary fluidchannel 344 but not into fluid channels 346, 348. Depending on whetheror not the second negative pressure source functions as a closed valvewhen not activated (thereby restricting fluid flow through the pressuresource), fluid in the second fluid channel can be drawn into the firstfluid channel. However, when it is desirable to prevent any flow, ashut-off valve 354 and/or one-way valve 356 and/or a negative pressuresource 352 that functions as a closed valve, e.g., a peristaltic pump,(when not activated) can be included in the case of multiple fluidchannels. The valve is positioned to allow flow into the input end ofthe fluid channel and to restrict fluid flow out of that input end.

Alternatively, it can be desirable to allow fluid transfer betweenparallel fluid channels. For example, it can be desirable to draw fluidfrom a reservoir into a first fluid channel, and then draw the samefluid sample into a second parallel fluid channel. This can beaccomplished, for example, by effectively unsealing the reservoirs,effectively unsealing the output end of the first fluid channel, andactivating a negative pressure source connected to the output end of thesecond parallel fluid channel. This flow arrangement could be used, forexample, to allow for the sequential analysis of a single sample inmultiple parallel fluid channels configured to analyze a sample.

According to certain embodiments, the system can include multiple flowchannels arranged in a serial arrangement. As shown in FIG. 3, the first316 and second 322 reservoir output ducts can be fluidically connectedto an input end of a first fluid channel 340. An output end of the firstfluid channel 340 can be fluidically connected to an input end of asecond fluid channel 342, and an output end of the second fluid channel342 can be fluidically connected (directly or indirectly) to thenegative pressure sources 328, 352. According to certain embodiments,fluid can be selectively drawn into the first secondary fluid channel,and allowed to stop (by, for example, deactivating the negative pressuresource) in the first secondary fluid channel before being subsequentlydrawn into the second secondary channel connected in series. This flowarrangement could be used, for example, to allow for the sequentialanalysis, including fixed and/or variable incubation and/or analysisperiods, of a single sample in multiple parallel fluid channelsconfigured to analyze a sample.

According to certain embodiments, the system can be configured such thatfluid does not flow into the primary fluid channel unless both thenegative pressure source is activated and at least one reservoir isunsealed. In the case of multiple negative pressure sources, the systemcan thus include auxiliary cut-off valves and one-way valves, asdiscussed above. These auxiliary elements can be contained in otherembodiments as well.

Additionally, unwanted fluid flow can be controlled by using gravity inorder to maintain it in a desired location, e.g., in a givenreservoir(s). For example, the connection path between a given reservoirand a given fluid channel can include the fluid being drawn to a heightabove the fluid level in the reservoir, such that inadvertent orunwanted fluid flow is eliminated or minimized absent the activation ofthe negative pressure source and venting, opening, of the appropriatevent. Unwanted fluid flow can also be minimized and/or eliminated incertain embodiments by including a barrier between or extending theseparation of the connections of the multiple reservoirs into a commonpath leading to the fluid channel.

The negative pressure source used to selectively draw fluid into thefluid channel can be any pressure source capable of drawing/moving afluid. The negative pressure source can be, e.g., a pump, including apump chosen from a peristaltic pump, a suction pump, a syringe pump, andan adsorption pump; an evacuated receptacle or cylinder; or a negativepressure source resulting from a chemical reaction, e.g., a reactionthat yields a net reduced volume, such as the condensation reaction,2H₂(g)+O₂(g)→2H₂O(1). The selection of a negative pressure source candepend, among other things, on the compatibility of the negativepressure source with the fluid, the viscosity of the fluid, the overallresistance of the fluidics system, the required flow rate, the capacity,the size and/or weight of the negative pressure source, the electricalrequirements of the negative pressure source, and/or the reliability ofthe negative pressure source. The flow rate of the fluid can be, forexample, nl/min to ml/min.

According to certain embodiments, the reservoirs can contain multiplesub-reservoirs. For example, a first sealable reservoir can include afirst and a second fluid chamber. Each chamber can have a fluid inputduct for withdrawing the fluid from the reservoir and an output endconnected to the primary fluid channel input end The vent can beconfigured to selectively seal or unseal both fluid chambers. The systemcan be configured to selectively draw fluid into the primary fluidchannel from at least one of (1) the first and second fluid chambers and(2) the second reservoir, when the negative pressure source connected tothe secondary fluid channel is activated and the respective chambers orreservoir is unsealed. In FIG. 5, reference number 516 designateschambers.

According to certain embodiments, the primary fluid channel can includea first and a second secondary fluid channel. Each of the secondaryfluid channels can contain input and an output end. The first sealedreservoir can contain first and second fluid chambers. Each of thechambers can contain a fluid input and output duct connected to thefirst and second secondary fluid channel input ends. The vent can beconfigured to selectively seal or unseal both of the fluid chambers. Thesystem can be configured to selectively draw fluid into at least one ofthe secondary fluid channels from at least one of (1) the first andsecond fluid chambers and (2) the second reservoir, when the negativepressure source is activated and the respective chambers or reservoir isunsealed.

The negative pressure source can include first and second negativepressure sources connected, respectively, to the first and secondsecondary fluid channel output ends, when, for example, the secondaryfluid channels are arranged parallel to each other. According to certainembodiments, the system can be configured to selectively allow fluid tobe drawn into one or more of the secondary fluid channels from the firstand/or second fluid chamber, and/or (2) the second reservoir when thenegative pressure source connected to the secondary fluid channel isactivated and the respective chamber or reservoir is unsealed, open.

According to certain embodiments, the system can be an analysis system.For example, the system can be configured to analyze at least onesample, such as a fluid sample or a sample dispersed in a fluid, for thepresence or absence of a given analyte. For example, the fluid channelcan be configured to be responsive or sensitive to the presence orabsence of the analyte. Thus, according to certain embodiments, thesample fluid can be selectively drawn into the fluid channel, where itcan interact with a surface or species sensitive to its presence orabsence, or otherwise be probed, such as probed optically, magnetically,chemically, radioactively, and/or electrically. According to certainembodiments, at least one of the first and second reservoirs isconfigured to contain at least one sample fluid. For example, the samplefluid can be introduced into and/or stored in a reservoir prior to beingselectively drawn into the primary fluid channel. The primary fluidchannel can be the location of a detector for analyte detection and/oridentification.

According to certain embodiments, the analysis can further involveselectively introducing at least one reagent fluid into said primaryfluid channel. For example, the reagent fluid can contain a rinsesolution to remove excess sample; or a reactive solution to react withresidual sample or species in the primary fluid channel. According tocertain embodiments, reagents can be introduced into the fluid channelany of prior to, simultaneously with, or subsequent to (and combinationsthereof) the introduction of the sample into the fluid channel.According to certain embodiments, at least one of the first and secondreservoirs can be configured to contain at least one reagent fluid. Forexample, the reagent fluid can be introduced into and/or stored in areservoir prior to being selectively drawn into the primary fluidchannel.

According to certain embodiments, the system can contain a waveguide.For example, at least one internal side of the primary fluid channel canbe a waveguide, such as a single mode or multi-mode waveguide. Forexample, waveguides as disclosed in U.S. Pat. Nos. 6,192,168 and6,137,117, the disclosures of which are incorporated herein byreference, can be used. According to certain embodiments, the system canfurther contain a waveguide for surface-sensitive optical detection ofan analyte in a fluid sample. For example, at least one internal side ofthe primary fluid channel can be a waveguide.

According to certain embodiments, the system can further include amulti-mode waveguide for surface-sensitive optical detection of ananalyte in a fluid sample. The multi-mode waveguide can have a surfacehaving a patterned reflective coating. The patterned reflective coatingdefines a reflectively coated region, e.g., and having an opticallyexposed region on the surface. The optically exposed region can besensitive to the analyte so as to produce an alteration of the opticallyexposed region which is indicative of the presence of the analyte in thesample. The alteration is detectable by launching a light wave into thewaveguide to generate an evanescent field on the patterned surface, andthen detecting an interaction of the first optically exposed region withthe evanescent wave. According to certain embodiments, the opticallyexposed region of the waveguide can define at least part of at least onesurface of the primary fluid channel.

According to certain embodiments, the system can further include awaveguide sensing system. The waveguide sensing system can contain, forexample, a plurality of waveguides, each waveguide having a firstsurface, a second surface opposing the first surface, and an end surfaceessentially perpendicular to the first and second surfaces. The firstsurface of each of the waveguides can have analyte recognition elementsthereon. This system can further include a waveguide holder to whicheach of the waveguides are secured, and an optical detector positionedopposite the end surface of at least one of the waveguides. According tocertain embodiments, at least one of the first surfaces can define atleast part of at least one surface of the primary fluid channel.

According to certain embodiments, at least one of the reservoirs of thesystem can contain an internal cavity configured in such a manner as tobe sealed from contact with an external atmosphere. For example,according to certain embodiments, the at least one internal cavity canbe connected to a vent that is configured to selectively connect anddisconnect the respective internal cavity from contact with the externalatmosphere. According to certain embodiments, the vent can be configuredto switch, in a binary fashion, between an “opened” and a “closed”position. Valves can be configured to be fully opened, partially opened,and fully closed and variation (including temporal) and combinationthereof.

According to certain embodiments, valves can be chosen from one-wayvalves, two-way values, multi-way valves, and proportional valves, andcombinations thereof. For example, if the valve is a one-way valve, itcan be switched between an opened and closed position. Two-way andmulti-way valves can be used, for example, to connect a reservoir orcavity to multiple external pressures, including atmospheric, positive,and negative, and/or to additional fluid supplies. Valves can also beconfigured to open and close multiple reservoirs or cavities. Forexample, an input of a two-way valve can be connected to a givenpressure source, one of the two valve outputs can be connected to onereservoir or cavity, and the second valve output can be connected toanother reservoir. Then, for example, the valve can be used toselectively connect either of the two (or more) reservoirs to thepressure source.

According to certain embodiments, a valve V comprising one input I andtwo (or more) outputs O1 and O2 can be used to selectively seal and/orunseal two (or more) reservoirs, R1 and R2. For example, input I can beconnected to the atmosphere (or a positive pressure source) with outputsO1 and O2 connected to reservoirs R1 and R2, respectively. When valve Vis configured to connect I to O1 but not O2, R1 will be unsealed and R2will be sealed. Likewise, when valve V is configured to connect I to O2but not O1, R2 will be unsealed and R1 will be sealed

According to certain embodiments, the system can be configured tosimultaneously have fluid drawn from the first and/or second reservoirinto the primary fluid channel at a first and/or a second flow rate,respectively, when the difference between the first and second flowrates is proportional to a difference in the unsealing of the first andsecond vents. According to certain embodiments, the system can beconfigured to selectively have fluid drawn from the first and secondreservoirs into the primary fluid channel at first and second flowrates, respectively, when the difference between the first and secondflow rates is proportional to the differential fluid flow resistance.The differential fluid flow resistance is adjusted by the sealing andunsealing of the first and second vents.

According to certain embodiments, at least one of the vents or valvescan be a proportional valve configured to partially or fully unseal areservoir. For example, to favor fluid flow from a first reservoir, aproportional valve can be connected to the first reservoir which canthen be opened to a relatively greater degree to a given pressuresource. At the same time a second reservoir connected to a secondreservoir can be opened to the same pressure source to a relativelylesser degree. According to certain embodiments, the differential fluidflow can be at least partially controlled by the relative pressure ofthe pressure sources to which the reservoirs are connected. For example,to favor fluid flow from a first reservoir, it can be vented (opened) toa relatively high pressure source while a second reservoir can beconnected to a relatively low pressure source. According to certainembodiments, differential fluid flow can be controlled by anycombination of proportional valves, relative vent source pressures,fluid viscosities, fluid channel diameters, fluid channel surfaces(e.g., rough, smooth, hydrophobic, hydrophillic, chemically derivatized,biologically derivatized, etc.), and pressure and current of the one ormultiple negative pressure sources.

According to certain embodiments, the system can further include asystem relief vent connected to the primary flow channel. For example,the system relief vent can be configured to seal or unseal, open orclose, the primary flow channel from contact with an externalatmosphere. According to certain embodiments, when the system reliefvent is in a closed or an open position, fluid flow from thereservoirs/chambers into the primary fluid channel is respectivelyenabled or disabled. According to certain embodiments, the system reliefvent can be configured to allow a fluid, such as air and/or any of itscomponent gases, to fill the primary fluid channel, and/or displace avolume of the fluid previously contained therein. The previous fluid canbe, for example, a sample or reagent fluid, as discussed further herein.

According to certain embodiments, a reservoir can be selectivelyconnected to atmospheric pressure or a positive pressure source that isconfigured to apply pressure greater than atmospheric pressure or anegative pressure source, that is configured to have a pressure lessthan atmospheric pressure to the unsealed reservoir.

According to certain embodiments, the system can further contain anauxiliary fluid reservoir and a connection valve. The auxiliary fluidreservoir 335 can be connected through the connection valve 337 to anauxiliary input duct 339 of at least one of the first and secondreservoirs. According to certain embodiments, the system can beconfigured to selectively have a fluid drawn from the auxiliary fluidreservoir into the first and/or second reservoir when the negativepressure source is activated, the connection valve is open, and therespective reservoir is closed or not vented to the atmosphere.

The connection valve can be a multi-way connection valve, configured toselectively connect the auxiliary input to a source chosen from theatmosphere, a positive pressure source, a negative pressure source, anda fluid reservoir. According to certain embodiments, a single valve canbe used to seal or unseal a reservoir, as well as the connection valveto connect the reservoir to the auxiliary fluid reservoir.

According to certain embodiments, the sizes and dimensions of the fluidchannels, including the primary and secondary fluid channels, can beconfigured to control a range of dynamic and static parameters,including, for example, the fluid flow rate, capacity, resistance, andturbulence. According to certain embodiments, the primary fluid channeland/or the connecting channels and/or other fluid channels in the systemcan be configured to have minimal cross-sectional dimensions such thatthe selective fluid drawing can be turbulent fluid flow.

According to certain embodiments, the primary fluid channel and/or theconnecting channels and/or other fluid channels in the system may beconfigured to have minimal cross-sectional dimensions such that theselective fluid drawing may or may not be a low Reynolds number fluidflow.

According to certain embodiments, the primary fluid channel and/or theconnecting channels and/or other fluid channels in the system may beconfigured have minimal cross-sectional dimensions such that theselective fluid drawing may or may not be a low Reynolds number fluidflow when the fluid has a density less than five times the density ofwater.

According to certain embodiments, the primary fluid channel and theconnecting channels are configured to have minimal cross-sectionaldimensions such that the selective fluid drawing may or may not be a lowReynolds number fluid flow when the fluid is an aqueous fluid.

According to certain embodiments, the system can further include a firstconnecting channel and a second connecting channel, wherein first andsecond reservoirs are connected to the primary fluid channel input byfirst and second connecting channels, respectively. The connectingchannels, the primary fluid channels, the secondary channels andreservoir/chamber output ducts can have minimum cross-sectionaldimensions greater than 1 micron. For example, the range of thecross-sectional size of any of the ducts and/or channels in which afluid moves can be at least 10% greater than the largest particle sizefound in any of the fluids, e.g., whether a sample, a reagent or aindicator.

According to certain embodiments, the system can include athree-dimensional fluid circuit (or fluid cube) comprising at least oneof the first and second reservoirs and the primary fluid channel.According to certain embodiments, the fluid circuit can include a seriesof layers, where the individual layers comprise at least partialelements of the fluid circuit, such that, when some or all of the seriesof layers are fused (or joined) together, complete elements of the fluidcircuit are formed.

According to certain embodiments, at least partial elements are formedby at least one of molding and mechanical, chemical, thermal, andoptical etching. For example, the fluid circuit can include elementsformed using injection molding techniques, as well as elements formedusing other molding techniques, including blow molding.

According to certain embodiments, the fluid circuit can further includea first connecting channel and a second connecting channel, wherein thefirst and second reservoir output duct ends are connected to the primaryfluid channel input ends by first and second connecting channels,respectively. The fluid circuit can also be configured, for example, sothat the first and second connecting channels have first and secondinput ends. These input ends of the connecting channels can be connectedto the first and second fluid output ducts, respectively. The commonchannel can have a first and a second end, where the first end can beconnected to the second ends of the connecting channels, and the secondend be connected to the input of the primary fluid channel input ends.

According to certain embodiments, the first and second connectingchannels can further be J-shaped connecting channels, where the lowerends of the J-shaped connecting channels can be connected to each of thereservoirs and the upper ends of the connecting channels can beconnected to the common primary channel and/or secondary channels. Theconnecting channels can further include a barrier. The barrier isconfigured to inhibit fluid flow between the first and second connectingchannels.

According to certain embodiments, the fluid circuit can further includeat least one of a first pressure duct and a second pressure duct, wherethe first and second pressure ducts connect the first and second ventsto the first and second reservoirs, respectively.

According to certain embodiments, the system can be a portable analysissystem, that includes a three dimensional fluid circuit. The fluidcircuit can include a first sealed reservoir. The first sealed reservoircan include a first fluid output duct that is fluidically connected tothe primary fluid channel input, and a first vent configured toselectively seal and/or unseal (open or close) the first reservoir. Thefluid circuit can further include a second sealed reservoir having asecond fluid output duct fluidically connected to the primary fluidchannel input, and a second vent configured to selectively seal and/orunseal (open or close) the second reservoir. A negative pressure sourcecan be connected to the primary fluid channel output end. The system canbe configured, for example, to selectively draw at least one fluid fromat least one of the first and second reservoirs into the primary fluidchannel when the negative pressure source is activated and therespective reservoir vent is unsealed.

According to certain embodiments, the system can be configured toperform biological and/or chemical analysis. The system can alsocomprise a three dimensional fluid circuit that has a first reservoirhaving a first fluid output duct fluidically connected to a primaryfluid channel input, and a first vent configured to selectively sealand/or unseal the first reservoir. The system can further include asecond sealed reservoir having a second fluid output duct fluidicallyconnected to the primary fluid channel input, and a second ventconfigured to selectively seal and/or unseal the first reservoir. Anegative pressure source can be connected to the primary fluid channeloutput. The system can be configured, for example, to selectively drawat least one fluid from at least one of the first and second reservoirsinto the primary fluid channel when the negative pressure source isactivated and the respective reservoir is unsealed. The fluid circuitelements can be formed using molding or milling techniques. The circuitcan contain a series of layers, in which some or all of the layers ofthe series have at least partial elements of the fluid circuit. Some orall of the series of layers can be fused (or otherwise joined,permanently or temporarily) together to form completed elements of thefluid circuit. The at least partial elements are formed by, for example,at least one of molding and mechanical, chemical, thermal, and opticaletching. The fluid circuit can further include a first connectingchannel and a second connecting channel, where the first and secondfluid outputs are connected to the primary fluid channel input by firstand second connecting channels, respectively.

The system can further contain a common channel. It can be configuredsuch that the first ends of the connecting channels are connected to thefirst and second fluid outputs, respectively, and a first end of thecommon channel is connected to the second ends of the output connectingchannels, and a second end of the common channel is connected to theinput of the primary fluid channel input. The first and second outputconnecting channels can also have J-shaped connecting channelsconfigured such that the lower end of the J-shaped connecting channel isconnected to the reservoir, e.g., at the bottom of the reservoir. Theupper end of each connecting channels is connected to the commonchannel. The connecting channels can further include a barrierconfigured to inhibit fluid flow between the first and second outputconnecting channels. Additionally, the fluid circuit can further includeat least one of a first pressure duct and a second pressure duct, wherethe first and second pressure ducts connect the first and second ventsto the first and second reservoirs, respectively.

According to certain embodiments, the present invention comprises amethod of controlling fluid flow. The method can comprise, for example,selectively drawing at least one fluid from at least one of a first anda second reservoir into a primary fluid channel. The selective drawinginvolves activating a negative pressure source and unsealing one of thereservoirs. According to certain embodiments, the first reservoir cancontain a first fluid output duct fluidically connected to the primaryfluid channel input, and a first vent configured to selectively sealand/or unseal the first reservoir. According to certain embodiments, thesecond reservoir can contain a second fluid output duct fluidicallyconnected to the primary fluid channel input, and a second ventconfigured to selectively seal and/or unseal the second reservoir.According to certain embodiments, the negative pressure source can beconnected to the primary fluid channel output.

According to certain embodiments, the selective drawing of a fluid caninvolve (wholly, partially, and/or for a controlled duration and/orcycle) sealing at least one of the unselected reservoirs and/or (wholly,partially, and/or for a controlled duration and/or cycle) unsealing atleast one of the selected reservoirs, and drawing at least one fluidfrom at least one selected reservoir.

According to certain embodiments, the selective drawing can involvepartially unsealing at least one first selected reservoir and partiallyunsealing at least one second selected reservoir, and drawing fluid fromboth the first and second reservoirs. For example, partial opening meanspartially unsealing (or opening) a vent to partially open a reservoir toat least one of the atmosphere and applied pressure.

According to certain embodiments, unsealing a selected reservoir caninvolve connecting it to a first pressure source, and sealing a selectedreservoir can involve connecting it to a second pressure source, wherethe pressure of the first pressure source is greater than the pressureof the second pressure source. According to certain embodiments,unsealing a selected reservoir can involve opening a vent such that theselected reservoir is connected to atmospheric pressure, e.g., byreleasing the vacuum. According to certain embodiments, unsealing aselected reservoir can involve application of a pressure less than anatmospheric pressure to the selected reservoir. According to certainembodiments, sealing a selected reservoir can involve applying apressure greater than an atmospheric pressure to the selected reservoir.

According to certain embodiments, the present invention comprises amethod of performing an assay. The method can allow for the, forexample, selective drawing of a sample fluid from a sample reservoirinto a primary fluid channel. According to certain embodiments, theselected sample (reagent) fluid that is drawn can involve activating thenegative pressure source, unsealing the sample (reagent) reservoir, andsealing the reagent (sample) reservoir.

According to certain embodiments, at least one side of the primary fluidchannel is configured to at least one of capture, recognize, respond to,and detect at least one analyte. At least one side can contain awaveguide that can, for example, have a first optically exposed regionsensitive to a first analyte so as to produce an alteration of the firstoptically exposed region that is indicative of the presence of the firstanalyte in the sample. The alteration is detectable by launching a lightwave into the waveguide to generate an evanescent field at the patternedsurface, and then detecting an interaction of the first opticallyexposed region with the evanescent wave.

According to certain embodiments, the waveguide can contain a multimodewaveguide having a surface bearing a patterned reflective coating. Thepatterned reflective coating defining a reflectively coated region andan optically exposed region on the surface. The optically exposed regionis configured to produce an alteration that is indicative of thepresence of an analyte. The alteration is detectable by launching alight wave into the waveguide to generate an evanescent field at thepatterned surface, and then detecting an interaction of the opticallyexposed region with the evanescent wave.

According to certain embodiments, the at least one fluid has a densitynot less than an atmospheric density. The fluid may, for example,comprise a liquid, a gas having a density not less than an atmosphericdensity, and/or a mixture wherein the density of the mixture is not lessthan an atmospheric density.

According to certain embodiments, the at least one fluid can be adispersion, a solution, a suspension, or an emulsion. According tocertain embodiments, the at least one fluid can be an aqueous fluid.

According to certain embodiments, at least one fluid can be a biologicalor chemical specie. For example, at least one fluid can contain anantibody, antigen, toxin, drug, metabolite, polypeptide virus, protein,cell, amino acid, or amino acid sequence. For example, the fluid can bea buffer, stabilizer, preservative, enzyme, sugar or lack of ametabolite.

According to certain embodiments, the at least one fluid can be taggedlabels, including tagged labels selected from optically, radioactively,magnetically, chemically, biologically, and physically (such as massand/or size and/or shape) tagged labels.

According to certain embodiments, the invention pertains to a method andapparatus for delivery a fluid to a selected reservoir. For example, ifthe negative pressure source in FIG. 1 is a pump configured to push afluid towards the reservoirs, and one reservoir 116 is unsealed and theother reservoir 122 is sealed, the fluid will be selectively deliveredto the unsealed reservoir 116.

The invention will be further clarified by the following examples, whichare intended to be purely exemplary of the invention.

Example I

A schematic illustration of an exemplary fluid flow control arrangement400 is depicted in FIG. 4. Arrangement 400 includes three reservoirs416, 422, and 460 in which respective fluids 430, 432, 462 and gas space434 are contained. The reservoirs are all fluid-tight (enclosed).Fluidly connected to each reservoir is a respective pressure reliefvalve 464, 466, 468. Pressure relief valves can be manually or remotelyactuated to move between an open position where pressure relief or airis provided to the respective reservoir and a closed position where nopressure relief or air is provided to the respective reservoir. In thisarrangement, pressure relief valves are each automatically actuatedremotely by a suitable control 470 as schematically shown, and are in aclosed (default) position when not actuated. Extending into or near abottom of each respective reservoir is a respective outlet pathway orduct 418, 424, 472. The outlet ducts are connected by a manifold, 450,to a primary fluid channel, 410, which is in turn connected to anegative pressure, 428, as a pump. Any number of reservoirs can besimilarly connected to the manifold as long as the manifold hassufficient branches.

When it is desired to draw a selected fluid from the associatedreservoir, such as fluid 430 from associated reservoir 416 theassociated pressure relief valve 464 is actuated to move from the closedposition to the open position (as shown in FIG. 4). With this opening ofthe pressure relief valve, atmospheric air is now allowed to back fillthe reservoir. At the same time, or previously or subsequently, negativepressure source 428 is actuated to exert a negative pressure, e.g.suction, on all fluids in all reservoirs. However, as only reservoir 416has an open pressure relief valve 464, only fluid 430 is drawn fromreservoir 416 into outlet duct 418 and through manifold 450 to thedesired delivery point. In this manner, fluid 430 is preferentiallydrawn from reservoir 416 as air is permitted to flow into and back fillreservoir 416 through open valve 464 while reservoirs 422 and 460remained sealed from the atmosphere and hence comparatively resistant toflow into the outlet ducts 424 and 472. If more than one pressure reliefvalve is opened, then fluids from multiple reservoirs can be drawnthough manifold 450 simultaneously, and combined at the common outlet ofmanifold and then conducted towards the negative pressure source 428

It can thus be appreciated that the fluid flow control arrangement 400allows for selective is fluid flow from a selected reservoir to a usepoint, e.g., the primary channel or a detector in the primary channel.The necessity of passing the selected fluid through any valves or thenecessity of resorting to micro-scale fluidics channels is eliminated.Thus, while the system can or can not contain valves through which thefluids must pass, such valves are not required for all embodiments andproblems with valves and channels clogging due to contaminants in thefluid are avoided. It will further be appreciated that this arrangementis a reduction in both the overall size and power consumption comparedto other fluidics arrangements as the pressure relief valves can be maderelatively small since normally only a gas passes through and such asmall valve requires very little power.

Example II

Depicted schematically in FIG. 5 is a first embodiment of a portablebio/chemical analysis system 500 incorporating a fluid flow controlarrangement as broadly discussed above whereby a plurality of samplefluids can be first simultaneously analyzed and then can be furthersimultaneously analyzed after addition of one or more reagents. Thesystem includes a bio/chemical analysis device 574 having analyzingchannels 576 in which analysis of a fluid can be performed as is wellknown in the art. One surface of the analyzing channels 576 can be awaveguide for performing optical analysis. For example, a waveguide inthe plane of the figure co-extensive in area with the analysis device574 could be used. Each analyzing channel 576 includes an associatedinlet 578 and an associated outlet 580 as shown. Associated with eachanalyzing channel 576 is a sample reservoir/chamber 516 in which asample fluid 530 and air 534 are respectively provided. First pathwaysor ducts 518 respectively connect a bottom of sample reservoirs 516 torespective inlets 578 of analysis device 574 All sample reservoirs 516are connected to a common sample pressure relief valve 536 asschematically shown. When sample pressure relief valve 536 is opened,pressure relief (back fill air) is provided above each sample in eachreservoir.

Bio/chemical analysis system 500 also includes reagent reservoirs 582 inwhich reagent fluids 584 and air space 534 are respectively provided.Each reagent fluid is conducted through a second pathway to theassociated analyzing channel 576. This second pathway includes secondducts 586 respectively connected to a lower portion, i.e., below anupper level of each fluid 584 of each reagent reservoir 582, and acommon duct 588 connected to the tops of sample reservoirs 516. In thisembodiment where reagent fluid 584 is delivered to a selected reservoir,the second pathway includes ducts 518 as well to complete the path tothe analyzing channels 576. Each reagent reservoir has connected theretoa respective reagent pressure relief valve 590 as shown.

As shown in FIG. 5, the system further includes a pump 528 which servesas a source of negative pressure to draw fluids into and throughanalyzing channels 576 of analysis device. Pump 528 is connected to anoutlet duct 592 of a suitable manifold 550, whose inlet ducts 594 arerespectively connected to outlets 580 of analysis device. If desired, asystem pressure relief valve 596 is also connected to outlet duct 592 ofmanifold 550. System pressure relief valve 596 is opened to feed gas topump 528 and hence to disable any flow of sample or reagent fluids inanalysis system. One or more system pressure relief vents can also beconnected to inlets 578, and can not only disable fluid 530 or 584 flowthrough the channels 576, but also can be used to introduce air or gasinto the channels, e.g., 576 to displace the fluids 530 or 584 and/or todry interior surfaces of channels 576

With this system, it is possible to analyze sample fluids 530simultaneously with analysis device 574, both before and then after theaddition of one or two reagent fluids 584 to the sample fluid. Thus, inoperation, pump 528 is initially actuated after analysis device 574 ismade ready to analyze any associated fluid passing through respectiveanalyzing channels 576. Sample pressure relief valve 536 is thensimultaneously (or subsequently or previously) opened, allowing backfill air into all sample reservoirs 516. This allows the pump 528 todraw the associated sample fluid 530 from each respective reservoir 516through the associated analyzing channel 576, where analysis device 574conducts all or part of the needed analysis for a reading or analysis ofeach respective sample fluid. During this initial analysis step, reagentpressure relief valves 590 are all closed, so no reagent fluid is drawninto sample reservoirs.

After the first analysis step of the sample fluids is accomplished,sample pressure relief valve 536 is closed and a selected one (or both)of reagent pressure relief valves 590 is opened. This causes thenegative pressure created by pump 528 in each sample reservoir 516 tocause a flow of reagent fluid from whichever reagent reservoir 582 canbe back filled with air due to an open reagent pressure relief valve590. Thus, after a small time period of operation of pump 528 afteropening of one or more reagent pressure relief valves 590, a reagentfluid 584 is delivered to the associated analyzing channels 576 foranalysis by analysis device 574. If the sample fluid had beensubstantially depleted from the reservoirs, then relatively pure reagentmay be delivered to the channels. However, if the sample fluid has notbeen substantially completely removed, according to the embodiment shownin FIG. 5, the reagent could be mixed with the sample fluid inreservoir. According to one mode of operation, one of the regent fluidswould be a wash fluid, such as a buffer fluid, to wholly or partiallyrinse remaining sample fluid out of reservoirs and channels. Then, forexample, a second reagent fluid can be delivered through reservoirs intochannels without mixing with sample fluids.

Where required, the amount of reagent fluid delivered to each samplereservoir can be varied as desired where the rate of flow of reagentfluid through ducts is known and the associated open pressure reliefvalve is closed after the desired flow volume is achieved (after whichsample pressure relief valve is opened again). Alternately, the amountof reagent fluid in each reagent reservoir can be known, and flowmaintained until the associated reagent reservoir is emptied. Similarly,the amount of sample fluid in each sample reservoir can be controlled byknowing the initial volume as well as the flow rate through first ductsand inlets; and this control can include emptying of the sample fluidtherefrom so that only a reagent fluid is then drawn to the analysisdevice.

When considering the range of fluid types, channel/duct sizes, pumppressures, and substrate materials, the following may also beconsidered. The relief valve control arrangement for the fluidics systemoperates when the resistance to flow of a first fluid in a firstreservoir (due to surface tension, channel size, channel material, etc.)is less than the resistance to flow of a second fluid in the secondreservoir that has been sealed-off from the atmosphere. This differencein resistance between the flow of the first and second fluids should begreater than the potential of the negative pressure source at the flowrate used. Without being bound by theory, a relation analogous to Ohm'slaw can be used to express this requirement. That is, relief valvecontrol will operate under conditions such that:

R>P/I,

-   -   where:    -   R=R2-R1, where R2 is the resistance to fluid flow caused by        sealing the fluid from atmosphere and R1 is the resistance to        fluid flow due to factors such as fluid channel size, viscosity,        channel material, etc.; and    -   P is the pressure difference between the negative pressure        source and ambient or sealing pressure; and    -   I is the flow rate of the negative pressure source.

Example III

As shown schematically in FIG. 1, two reservoirs 116, 122 were connectedthrough a manifold 150 to a primary fluid channel 110 comprisingfluorescence detector, 133. The fluorescence detector was used to detecta fluorescent dye in one of the fluids 130, possibly water. Thereservoir 116 contained water. Reservoir 122 contained a 60 nM aqueoussolution of fluorescent dye Cy5, 132. Each reservoir was sealed, closed,to the atmosphere except that each was connected to vents 120, 126 tomicro relief valves 136 (“vent 1”) and (“vent 2”) (LFAA12034, The LeeCompany), respectively. The default closed position of the valve causedthe given reservoir to be sealed from the atmosphere. The relief valves136 could be individually actuated (via a 12 volt signal) to open agiven reservoir to atmospheric pressure. The negative pressure source128 was a peristaltic pump, running at 1.5 ml/min. It was used to drawfluid from each of the reservoirs and through the fluid channel 110comprising detector 133 to a waste collector (not shown). In thisconfiguration and as described above, when vent 120 was open the fluidin 116 (water) would be drawn through the detector by the pump. Thefluid, Cy5, 132 did not flow because of its greater resistance to flowresulting from the inability of air to replace back fill the fluid beingwithdrawn from the reservoir. The fluid in 124 would flow, exclusively,when vent 120 was closed and vent 126 was opened, and negative pressuresource 128 was activated.

As shown in FIG. 6, when vent 120 was opened and vent 126 was closed andthe negative pressure source 128 was activated (see control signal,solid line, right y-axis), the fluorescence detector recorded a signallevel of zero 698 (see fluorescence signal, line with points, lefty-axis). This indicated that the water was pulled through the system.However, when vent 120 was closed and vent 126 was opened (and negativepressure source was 128 was activated), the fluorescence signal 699 rosesharply (in arbitrary units) since the Cy5 solution in 122 was drawnthrough the system and detected. The slight delay of the signal rise ascompared to the opening of vent 126 was due to the finite distance thatthe fluid needed to flow from the T-junction (manifold 150) to thedetector. The tailing of the signal level to zero when 120 was open wasattributed to the detection of residual Cy5 in the fluid channels beingwashed out by the water.

Example IV

Depicted in FIG. 7 is a simplified (for convenience of illustration)fluid fluidics circuit which has been embodied in a modular block orcube 700 formed of a series of layers 702, 704, 706, 708, 709 (frombottom to top). Cube 700 was designed to fit into a preformed receptacleof a bio/chemical analysis device and to have an overall small size of,for example, 75 cm³ where six sample reservoirs 716 and six reagentreservoirs 782 were provided for processing. Cube 700 can be designedfor use in a number of different assay formats (parallel, individuallyselective, etc.), depending on the requirements. In this embodiment,each sample reservoir 716 and corresponding (paired) reagent reservoir782 was each selectively connected to a respective analyzing channel inthe analysis device, with all sample fluids or all reagent fluids beingconducted at the same time. Six different fluid samples were analyzedsimultaneously. Each sample can be analyzed for six different analyteswhen combined with an array sensor, e.g., as disclosed by M. J.Feldstein et al., Array Biosensor: Optical and Fluidics Systems,Biomedical Microdevices 1(2) (1999), and Dodson et al., Fluidics Cubefor Biosensor Miniaturization, Analytical Chemistry, 2001, (thedisclosures of which are incorporated in their entireties by reference).Alternately, cube 700 could be suitable for use with other assaymethodologies as desired.

Cube 700 is essentially a passive fluid circuit in that it operateswithout the use of any internal valves or meters. Internal valves and/ormeters could, of course, be added. Instead, the fluid circuit operatesby use of external pressure relief valves and a pump in the analysisdevice. As shown, cube 700 was constructed of stacked layers of, forexample, a thermoplastic such as poly(methylmethacrylate) for layers704, 709 but optionally having a lower surface of layer 702 made of acompressible material such as neoprene, for pressure based sealing ofthe cube 700 to, for example, an assay flow cell as described in M. J.Feldstein et al., Array Biosensor: Optical and Fluidics Systems,Biomedical Microdevices, 1, (2), 1999. Likewise, a lower surface oflayer 709 and/or an upper surface of layer 708 can optionally be madefrom a compressible material, for pressure based sealing of layer 709 toan upper surface of layer 708. When aligned, using, for examplealignment holes 711 and joined together into cube 700, the essentiallytwo-dimensional features of each layer provide the fluid circuitrequired for the present invention. Layers 704, 708 were stacked andthen fused into cube under moderate pressure and heating to just abovethe glass transition temperature so that cube was made fluid-tight.Other methods of joining the layers together, such as adhesives orapplied pressure and compressible seals, could also be used in place ofor in combination with the thermal fusing process. The top layer, layer709, can be attached to the cube using bolts in bolt holes 713 (withcorresponding receptacles for the bolts in at least one of layers702-708) or a bolt receptacles positioned below layer 702, that sealsthe cube using a gasket arranged between the layer 702 and the rest ofcube. Sample fluids and reagent fluids can be placed into the cubebefore top layer 702 is attached thereto, or if desired, a dried reagentor sample can be placed into reagent reservoirs 786 before sealing foruse when fluid is later added after sealing.

As shown in FIG. 7, cube 700 includes holes in each layer forming samplereservoirs 716, reagent reservoirs 782, outlet channels 780 (connectedto the analyzing channels and the source of negative pressure), firstducts 786, and second ducts 786. In layer 704, suitable fluidconnections 715 are made at the bottoms of sample reservoirs 716 to thebottoms of first ducts 718, and similarly suitable fluid connections 717are made at the bottoms of reagent reservoirs 782 to the bottoms ofsecond ducts 786. In layer 708 the tops of outlet channels 780therebeneath are connected by fluid connections 719 to the tops of firstducts 718 and similarly by fluid connections 721 to the tops of secondducts 786. Finally, as shown in layer 708, a network 723 of fluidconnections can connect the tops of sample reservoirs 716 with anexpanded vent cavity 725 whose top is then connected to the samplepressure relief valve (provided in the analysis device) though smallvent hole 727; while a network 729 of fluid connections connects thetops of reagent reservoirs 782 with an expended vent cavity 731 whosetop is then connected to the reagent pressure relief valve (alsoprovided in the analysis device) though small vent hole 733.Conveniently, all of the holes, channels, and ducts are formed in cubeby the simple drilling or machining.

With the fluid circuit embodied in cube 700, six selected sample fluidsare conveniently inserted into respective sample reservoirs 716 whilesix selected reagent fluids are similarly inserted into reagentreservoirs 782. Thereafter, the cube is inserted as a modular unit intoan analysis device adapted to receive the cube. The analysis device isthen actuated in a first operation to draw the sample fluids from eachsample reservoir 716 from the bottom thereof, through first ducts 718,and into outlet channels 780 for analysis in corresponding analyzingchannels of the analysis device. During this first operation, it will beappreciated that the pump (or alternatively pumps) is actuated. At thesame time that the sample pressure relief valve is opened so that airflows through each vent hole 727 to each sample reservoir 716. Duringthis first operation, the reagent pressure relief valve is closed, sothat no reagent fluid is drawn from reagent reservoirs 782. Aftersuitable analysis of the sample fluids (or portions thereof), the samplepressure relief valve is closed and the reagent pressure relief valve isopened, switching the flow through outlet channels 780 from theassociated sample fluids to the associated reagent fluids.

It is anticipated that a standard cube would have reservoirs 716, 782each sufficient to hold about 0.4 ml of fluid. However, with a modulardesign, the reservoir volume could be increased or decreased as desired,prior to annealing or assembling of cube, by simply adding orsubtracting layers 706. Layers 706 could thus be designed to add orsubtract to the volume of reservoirs 716 and 782 in 0.2 ml increments asdesired. In addition, if the presence of residual sample fluid in outletchannels 780 causes analysis problems after switching is made, separatesample and reagent outlet channels could be easily provided instead ofthe common outlet channels 780.

The cube is designed to operate with currently available miniatureperistaltic pumps. Even if six such pumps were used, all six pumps wouldbe expected to add only about 120 cm³ to any analysis device and woulddraw minimal current (50-75 mA max per pump). This makes such pumps andcube ideal for extended battery operation contemplated for portablebio/chemical analysis systems.

While the fluidics system as described above has been depicted as havingtwo, three or six sets of reservoirs, it can be appreciated by those ofordinary skill in the art that there is really no limit to the number ofreservoirs that can be used either in a series or in a parallelarrangement, or combinations thereof. In addition, while the fluidicssystems have been disclosed as being used to draw fluids out ofdifferent reservoirs, the present invention is also applicable tocontrolling fluids being selectively pumped into a reservoir. Further,while reservoirs of glass or plastic are typical, the present inventionis applicable to reservoirs of almost any material, such as metal orceramic, so long as the reservoir can be effectively sealed from theatmosphere. Still further, any suitable pressure relief valve, whethermanual or automatic, can be used, including physical and chemical ventvalves where the swelling and contracting of a polymer could function asa vent.

FIG. 8 shows a simplified three-dimensional perspective view of twosample reservoirs, two-reagent reservoirs fluidics system that issimilar to the six sample, six reagent system of FIG. 7.

Example V

A fluidics cube, substantially as described in Example IV, was used witha patterned multimode waveguide to perform bio-chemical analysis onseveral samples. Staphylococcal enterotoxin B (SEB) and anti-SEBantibodies were obtained from Toxin Technologies (Sarasota, Fla.). Togenerate capture antibodies, a long-chain derivative of biotin,N-hydroxysuccinimidyl ester (EZ-Link NHS-LC-Biotin; Pierce, Rockford,Ill.) was attached to the anti-SEB at a 10:1 biotin:protein ratio asrecommended by the manufacturer. Labeled protein was separated fromunincorporated biotin using a Bio-Gel P10 column, (Bio-Rad, Hercules,Calif.). Fluorescent tracer antibodies were prepared by labelinganti-SEB antibodies with Cy5 bisfunctional reactive dye (λ_(ex)=649 nm,λ_(em)=670 nm, Amersham Life Science Products, Arlington Heights, Ill.)according to the manufacturer=s instructions. Dye to protein ratiosranged from 2.5 to 4.0.

Silver-clad slides (Opticoat Associates, Protected Silver) (Feldstein,M. J., Biomed. Microdevices, 1999, 1:2, pp. 139-153 (the disclosure ofwhich is incorporated herein in its entirety by reference)) were cleanedin a potassium hydroxide (KOH) solution (10 grams KOH in 100 mlisopropanol) for 30 minutes at room temperature in a Coplin jar. Theslides were rinsed thoroughly with de-ionized water and dried using astream of nitrogen.

NeutrAvidinJ (Pierce, Rockford, Ill.) was immobilized on the silveredside of the slides essentially according to the method of Bhatia et at.,(Bhatia, S. K. et al., Anal. Biochem., 1989, 178, pp. 408-413 (thedisclosure of which is incorporated herein in its entirely byreference)) and modified to prevent removal of the silver cladding. Thecleaned slides were incubated for 1 hour in a 2% silane solution (1 ml3-mercaptopropyl triethoxysilane in 50 ml anhydrous toluene) in a glovebag under nitrogen. The slides were washed three times in anhydroustoluene and air-dried briefly on a lint-free cloth, silver side up. Thesilanized slides were incubated for 30 minutes at room temperature inGMBS solution (12.5 mg B[g-maleimidobutyryloxy]-succinimide ester in0.25 ml dimethyl sulfoxide to which 43 ml absolute ethanol were added),then washed three times in de-ionized water and placed in a fresh Coplinjar. Finally, the slides were incubated in a NeutrAvidin solution (100Fg/ml in 10 mM sodium phosphate buffer, pH 7.4) for 2 hours at roomtemperature, and then rinsed three times in 10 mM sodium phosphatebuffer, pH 7.4, prior to storing them in the same buffer.

Physically isolated patterning, PIP, (Rowe, C. A., Anal. Chem., 1999,71, pp. 433-439 (the disclosure of which is incorporated herein in itsentirely by reference)) was used to form an array of recognitionelements on a planar waveguide. Briefly, a patterning multi-channel flowcell was placed on the surface of a waveguide that had been coated withNeutrAvidin. Biotinylated anti-SEB antibodies were introduced into thechannels of the flow cell (each channel can contain a separaterecognition molecule) and incubated overnight at 4° C., producingcolumns of the capture antibody patterned on the waveguide surface,perpendicular to its length. When used in combination with amulti-channel flow cell aligned orthogonal to the patterned captureantibody, the sensing surfaces present a 2-dimensional array ofrectangular recognition elements.

The PIP method used custom designed and molded flow cells, whichconsisted of six parallel channels fabricated in widths from 0.75 to 1.5mm. These flow cells were made from MED-6015 silicone elastomer,polydimethylsiloxane, PDMS (NuSil Silicone Technology), an elastomerknown for its ability to mold and reproduce three-dimensionalstructures. PDMS, once cured, is highly inert, i.e., antibodies andantigens are not degraded by exposure to PDMS. In addition, theelasticity and hydrophobicity of PDMS enables temporary, fluid-tightseals to be made using only moderate pressure. The PDMS patterning andassay flow cells were molded from a polymethyl-methacrylate (PMMA)master mold created using a CNC mill (CNC Software Inc., Tolland,Conn.). The PDMS flow cells were reusable. They were cleaned and used toprepare dozens of patterned substrates.

Cube layers were designed using MasterCam 8.0 software (CNC SoftwareInc., Tolland, Conn.) and were manufactured from 0.25 inch clear castacrylic (AtoHaas North America, Inc., Philadelphia, Pa.) using a 3-axisservo router (Techno-Isel, Hyde Park, N.Y.). Each layer of acrylic wasmilled to contain a hole or groove or both. When the layers werealigned, the holes and grooves combined to form a three-dimensionalnetwork of channels and reservoirs. The cube was designed to contain abank of sample reservoirs on one side and reagent reservoirs on theother with channels between the reservoirs. Other features that weremilled into the layers formed holes for alignment of the pins and holesthat were used to attach the cube to the flow manifold. To form a solidcube, the layers were secured with stainless steel pins then lightlyclamped in a vise and heated to 140° C. for 3 hours. After cooling toroom temperature, stainless steel tubing was inserted into the twelveexit holes to create exit ports. The tubing was secured with a smallamount of 5 Minute® Epoxy (Devcon, Inc., Danvers, Mass.). After theepoxy had set, the tubing was cut to the desired length using avariable-speed rotary tool equipped with a cut-off wheel (Dremel, Inc.,Racine, Wis.). Alternatively, the cube was created by applying Weld-On3, an acrylic solvent cement, (IPS Corporation, Gardena, Calif.) to alayer then carefully placing the next layer on top of it, with lightmanual pressure and allowing the cement to dry. Layers were built up inthis manner until the entire cube was created. After cementing thelayers into a cube, it was placed in a vise under light pressure andheated to 140° C. for 3 hours. Each cube was tested for proper fluidflow and also checked for leaks between reservoirs and channels or tothe exterior.

A flow manifold containing six channels and entry/exit holes for fluidpassage was designed using MasterCam 8.0 software (CNC Software Inc.,Tolland, Conn.). The flow manifold was manufactured from 0.25″ clearcast acrylic (AtoHaas North America, Inc., Philadelphia, Pa.) or blackLucite7.™. cast acrylic (IC Acrylics, Wilmington, Del.) using a 3-axisservo router (Techno-Isel, Hyde Park, N.Y.). In the case of the manifoldcontaining the PDMS gasket (Leatzow et al., submitted), the flowchannels were 2.74 mm wide.times.38.1 mm long and 2.54 mm deep. The PDMSbarrier separation between each channel measured approximately 1.1 mm.

The flow manifold with the PDMS gasket was attached to the glasswaveguide through compression in a cassette assembly. The assemblyincluded the acrylic flow manifold with integrated PDMS gasket, theglass waveguide, a bottom aluminum mounting bracket, and nylon mountingscrews. The waveguide was held in place between the flow manifold andthe mounting bracket by tightening the mounting screws. The cube wasattached to the top of the flow manifold by a pair of nylon mountingscrews. The screws extended above the top surface of the manifold andentered into the cube from below.

Following component assembly, the assay module (cube, flow manifold, andwaveguide) was placed on the detector. To verify the system's integrityand block nonspecific binding, the cube's reservoirs were filled withphosphate buffer saline containing 0.05% Triton® and 1 mg/ml bovineserum albumin, PB STB, which was drawn through the flow manifold withnegative pressure from a downstream peristaltic pump. During the PBSTBflow-through, images of the waveguide were captured to check for flowand leaks. To assess nonspecific binding, 200 μl of 10 μg/mlCy5-anti-SEB antibody solutions were loaded into one bank of reservoirsand drawn through the system. The system was flushed with 250 μl ofPBSTB per reservoir and an image was captured. The image showednegligible binding of Cy5-anti-SEB antibody to the waveguide or to theedges of the flow manifold touching the waveguide.

Once the system checks were completed, 250 μl of each dilution of SEB(0-50 ng/ml) were loaded into one bank of sample reservoirs. The otherbank of reservoirs was loaded with 250 μl Cy5-anti-SEB, fluorescenttracer antibody, at 10 μg/ml. By opening and closing the appropriate airvents, the reservoirs containing the tracer antibodies could be closedand the reservoirs containing the samples could be opened, allowing onlythe sample reservoirs to flow. An off-board peristaltic pump at a flowrate of approximately 0.35 ml/min was used to create negative pressuredownstream of the assay module. After five minutes, the samplereservoirs had been drained and the vents were then closed. The tracerantibody reservoirs were then opened, and flow was confirmed bycapturing an image during the flow-through. After five minutes, theantibody reservoirs had been drained. The antibody reservoirs werefilled with PBSTB and the buffer flushed through the flow manifold. Afinal image, demonstrating detection of various concentrations of SEBwas captured and analyzed.

Digitized images were analyzed using Scion Image (Scion Corporation,Frederick, Md.). To quantitate a region of interest (“spot”), a smallrectangular selection was outlined around it and the program calculatedthe average intensity of the pixels within the spot. Using the same sizerectangle, background readings were taken on either side of the spot andthe mean fluorescence of the background was subtracted from the valuedetermined for the spot. There were six spots per channel (per SEBconcentration) and their mean and standard deviations were reported.

Premature mixing of sample and reagent upstream of the waveguide surfacecould be minimized by configuring the flow path so that neither thesample nor the reagent flowed through the common channel, i.e., byseparating the fluids with an extended barrier.

Dilutions of SEB were loaded into the reservoirs of the cube and assayedin our detector system. FIG. 9 shows the pattern of signals captured bythe imaging system. The fluorescent signals of the spots were determinedby subtracting the mean fluorescent intensity of the adjacent regionswith no capture antibody (non-specific binding) from the fluorescentintensity of the region including the capture antibody. The netfluorescence for each capture antibody spot was plotted as a function ofSEB concentration. As shown in FIG. 10, the system was able to detectconcentrations of SEB from 5 to 50 ng/ml in a 200 μl sample, i.e., 1 to10 ng (36-360 fmoles) of SEB. Six samples were analyzed simultaneouslywith six assay replicates of each sample (i.e., six separate assayspots) in under 20 minutes.

Other embodiments of the invention will be apparent to those skilled inthe art from consideration of the specification and practice of theinvention disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the invention being indicated by the following claims.

1. A portable analysis system for conduction of biochemical and/orchemical analysis comprising: a three-dimensional fluid circuit; a firstenclosed reservoir having a first adjustable vent; a second enclosedreservoir having a second adjustable vent; a first passageway forreceiving a first fluid from said first reservoir; a second passagewayfor receiving a second fluid from said second reservoir; a primary fluidchannel; wherein the primary fluid channel is configured to have acharacteristic dimension such that the selective fluid drawing is not alow Reynolds number fluid flow; a first connecting channel connectingsaid first passageway upstream to said primary channel; a secondconnecting channel connecting said second passageway upstream to saidprimary channel; a multimode waveguide; a barrier configured to preventfluid flow between said first and second connecting channels; and anegative pressure source downstream of said primary fluid channel;wherein said first and second reservoirs and passageways are elements insaid fluid circuit; wherein said fluid circuit comprising elements and aseries of layers and at least one of said elements is formed usingmolding techniques and at least partial elements are formed by moldingand mechanical, chemical, thermal or optical etching; wherein each layerof a series of layers is at least a partial element of said fluidcircuit; wherein said layers are fused together to form completeelements of said fluid circuit; and wherein said negative pressuresource being configured for moving said first fluid but not said secondfluid to said primary fluid channel only when at least the negativepressure source is activated and when said first adjustable vent is notin a closed position and when said second adjustable vent is in a closedposition; and for moving said second fluid but not said first fluid tosaid primary fluid channel only when at least the negative pressuresource is activated and when said second adjustable vent is not closedand when said first adjustable vent is closed.
 2. The fluidics system ofclaim 1, wherein said fluidics system is configured to conduct analysisof at least one of said first and second fluid.
 3. The fluidics systemof claim 2, wherein said first and second fluids are analyzed in saidprimary fluid channel.
 4. The fluidics system of claim 1, wherein saidfirst fluid is a sample and said second fluid is a reagent.
 5. A methodof performing a biochemical analysis, comprising: moving a first fluidin a first reservoir having an adjustable first vent to a primary fluidchannel when said first adjustable vent is not in a closed position andnot moving a second fluid in a second reservoir having a secondadjustable vent in a closed position when a negative pressure source isactivated downstream of said primary fluid channel; wherein the primaryfluid channel is configured to have a characteristic dimension such thatthe selective fluid drawing is not a low Reynolds number fluid flow; andanalyzing said first fluid.
 6. The method of claim 5, wherein saidanalyzing step is performed in said primary fluid channel, and whereinin said primary channel an internal surface is configured to at leastone of capture, recognize, respond to, and detect an analyte.
 7. Themethod of claim 6, wherein said primary fluid channel comprises awaveguide, wherein said waveguide as adapted for transmitting opticalsignals to a detector, and wherein said optical signal indicatespresence or absence of an analyte.
 8. The method of claim 7, whereinsaid waveguide comprises a multimode waveguide having a surface bearingpatterned, reflective coating, wherein said coating defines areflectively coated region and a first optically exposed region on saidsurface, wherein said first optically exposed region is configured toproduce an alteration indicative of the presence of a first analyte,wherein said alteration is detectable by launching a light wave intosaid waveguide to generate an evanescent field at said patternedsurface, and then detecting an interaction of said first opticallyexposed region with said evanescent wave.
 9. A method of controllingfluid flow, comprising: selectively drawing at least one fluid from atleast one of a first and a second reservoir into a primary fluidchannel, the selectively drawing comprising activating a negativepressure source and unsealing one of the reservoirs, wherein the primaryfluid channel is configured to have a characteristic dimension such thatthe selective fluid drawing is not a low Reynolds number fluid flow; andwherein the primary fluid channel comprises an input and an output;wherein the first reservoir comprises a first fluid output fluidicallyconnected to the primary fluid channel input, and a first ventconfigured to selectively seal and unseal said first reservoir; whereinthe second reservoir comprises a second fluid output fluidicallyconnected to the primary fluid channel input, and a second ventconfigured to selectively seal and unseal said second reservoir; andwherein the negative pressure source is connected to the primary fluidchannel output.